** Tags removed: verification-needed-noble-linux
** Tags added: verification-done-noble-linux
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Title:
[UBUNTU 24.04] IOMMU DMA mode changed in
Thanks Barbara for the verification!
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Title:
[UBUNTU 24.04] IOMMU DMA mode changed in kernel config causes massive
throughput degradation for
** Tags removed: targetmilestone-inin---
** Tags added: targetmilestone-inin2404 verification-done
verification-done-noble
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Title:
[UBUNTU
This bug is awaiting verification that the linux/6.8.0-40.40 kernel in
-proposed solves the problem. Please test the kernel and update this bug
with the results. If the problem is solved, change the tag
'verification-needed-noble-linux' to 'verification-done-noble-linux'. If
the problem still
** Changed in: ubuntu-z-systems
Status: In Progress => Fix Committed
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Title:
[UBUNTU 24.04] IOMMU DMA mode changed in kernel config
** Changed in: linux (Ubuntu Noble)
Status: In Progress => Fix Committed
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Title:
[UBUNTU 24.04] IOMMU DMA mode changed in kernel config
** Also affects: linux (Ubuntu Noble)
Importance: Undecided
Status: New
** Also affects: linux (Ubuntu Oracular)
Importance: Undecided
Assignee: Canonical Kernel Team (canonical-kernel-team)
Status: In Progress
** Changed in: linux (Ubuntu Noble)
Importance: Undecided
Many thanks for confirming, Niklas!
** Description changed:
SRU Justification:
[Impact]
* With the introduction of c76c067e488c "s390/pci: Use dma-iommu layer"
(upstream with since kernel v6.7-rc1) there was a move (on s390x only)
to a different dma-iommu implementation.
Well, 'make defconfig' is what I cannot use, since we have the Ubuntu specific
kernel options (and tools).
But since "not set" defaults to no, I guess it should be okay to explicitly set
CONFIG_IOMMU_DEFAULT_DMA_STRICT=n.
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Modification was sent to kernel teams mailing list:
https://lists.ubuntu.com/archives/kernel-team/2024-July/thread.html#151928
** Changed in: linux (Ubuntu)
Assignee: (unassigned) => Canonical Kernel Team (canonical-kernel-team)
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** Description changed:
SRU Justification:
[Impact]
- * With the introduction of c76c067e488c "s390/pci: Use dma-iommu layer"
-(upstream with since kernel v6.7-rc1) there was a move (on s390x only)
-to a different dma-iommu implementation.
+ * With the introduction of
** Description changed:
+ SRU Justification:
+
+ [Impact]
+
+ * With the introduction of c76c067e488c "s390/pci: Use dma-iommu layer"
+(upstream with since kernel v6.7-rc1) there was a move (on s390x only)
+to a different dma-iommu implementation.
+
+ * And with 92bce97f0c34
Looks like it's not sufficient to have IOMMU_DEFAULT_DMA_LAZY=y only
in addition IOMMU_DEFAULT_DMA_STRICT=n seems to be needed on top (otherwise the
build failed for me).
(Which I think is not super great upstream, one option should be fine -- with
the two kernel options, there are now two
Hi Niklas, thanks for the backgrounds.
So to sum it up:
The Ubuntu kernel config options for IOMMU_DEFAULT_DMA_LAZY and
IOMMU_DEFAULT_DMA_STRICT haven't changed since jammy/22.04:
5.15.0-1.1 to 5.15.0-115.125
CONFIG_IOMMU_DEFAULT_DMA_STRICT=y
# CONFIG_IOMMU_DEFAULT_DMA_LAZY is not set
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Title:
[UBUNTU 24.04] IOMMU DMA mode changed in kernel config causes massive
throughput degradation for PCI-related network workloads
To
Btw. I just checked the jammy kernel config options and jammy/22.04 had and
still has strict=yes:
$ lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description:Ubuntu 22.04.4 LTS
Release:22.04
Codename: jammy
$ uname -a
Linux maasrrc1 5.15.0-112-generic
Upstream commit b2b97a62f055dd638f7f02087331a8380d8f139a changes the
s390x defconfig's, which don't impact the Ubuntu kernel configs.
Looking at the configs for the 22.04 generic kernel,
'CONFIG_IOMMU_DEFAULT_DMA_STRICT=y' seems to be set for s390x on all
Ubuntu 5.15 generic kernel builds as
I just had a look at the Ubuntu kernel noble master-next tree and can find
commit:
"Revert "s390: update defconfigs"" under the hash b2b97a62f055
and I can see that it got reverted with that:
$ git show b2b97a62f055 | grep CONFIG_IOMMU_DEFAULT_DMA_STRICT
CONFIG_IOMMU_DEFAULT_DMA_STRICT
** Also affects: ubuntu-z-systems
Importance: Undecided
Status: New
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Title:
[UBUNTU 24.04] IOMMU DMA mode changed in kernel config
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